The invention relates to a heating device for heating merchandise, especially printed boards, comprising a feeding device provided in front of at least one heating line in the transport direction of the merchandise and a transportation device provided behind the heating line in the transport direction, wherein a number of heating zones/devices and/or cooling zones/devices or the like are associated with the heating line.
Such a heating device is known from DE 297 04 601. A heating line extending essentially transversely to the transport direction and leading the merchandise approximately around in a circular manner is thereby fed with merchandise in the form of printed boards by corresponding feeding devices, which merchandise is transported away from the heating line by corresponding transportation devices. The feeding and the transportation take place in horizontal planes in the direction of the transport direction, whereby said horizontal planes may be disposed so as to be offset to each other. A number of zones or devices for heating and cooling are positioned along the heating line. The corresponding heating zones or respectively devices serve, for example, the re-melting of solder paste, i.e. the so-called reflow soldering, the hardening of adhesives for fixing components on the printed boards, the drying of lacquer on the printed boards etc.
A corresponding heating zone may, for example, be formed of a region of the heating line, in which heated air is supplied. Also a direct heating by means of a heating device such as an infrared lamp or the like may take place. A cooling zone, may, for example, be disposed between two heating zones or heating devices, whereby the cooling may simply take place by the dissipation of heat to the environment in the cooling zone. Moreover, an active cooling device may be provided, which cools the merchandise to a certain temperature. Furthermore, a cooling gas may be correspondingly fed and discharged in the cooling zone analogously to the heating gas.
Due to the arrangement of the heating line the known heating device according to DE 297 04 601 is very compact and efficient in the exploitation of heating gas and cooling gas, which results from the vertically disposed heating line sections. The throughput of said known heating device is, however, not large enough to allow an operation without a delayed supply of printed boards or correspondingly laborious buffers.
The invention is, therefore, based on the object to improve a heating device of the aforementioned type by increasing the throughput of merchandise in a simple manner.
Said object is provided in connection with the features of the preamble of claim 1 by disposing at least two heating lines on top of each other, to which merchandise can be separately fed by the feeding device from a horizontal transport level, and by the transportation device separately discharging the merchandise from the heating lines back into a horizontal transport level. Both horizontal transport levels may be arranged so as to be offset to each other or may be arranged in one plane.
By disposing the at least two heating lines on top of each other, essentially double the number of printed boards or the like as merchandise can simultaneously be handled in the same period of time without requiring more space or additional feeding and transportation devices. Thus, the time required for processing such merchandise is reduced while the costs are decreased at the same time.
In order to be capable of taking the merchandise by the heating device according to the invention prior to the feeding thereof to the heating lines during a relatively fast feeding of the merchandise, and also to be able to buffer the same prior to the discharge, the feeding and for transportation devices may comprise a buffer for buffering a plurality of goods
The heating device according to the invention may also comprise more than two heating lines on top of each other, whereby, if, for instance, three, four or five heating lines are arranged on top of each other, the feed and the transportation of the merchandise by means of the corresponding feeding and transportation devices likewise take place separately.
Moreover, it is possible in accordance with the invention that at least two heating lines are disposed next to each other with each of said heating lines having a corresponding number of heating lines in levels on top thereof.
As the heating and/or cooling of the merchandise along the heating lines may take place in a protective gas atmosphere, corresponding lock devices may be arranged between the heating line and the feeding and transportation devices. Such a lock device is to prevent protective gas from escaping into the environment so as to guarantee a closed protective atmosphere.
In order to be able to carry off the protective gas from the lock device, each of said lock devices may comprise a suction implement.
When treating especially printed boards as merchandise it is generally an advantage if the heating takes place in a certain time and/or at a certain temperature gradient, a processing at a certain temperature level for a predetermined time, and if a cooling and, if required, an intermediate heating takes place in an analogous fashion. This may advantageously be effected by being able to adjust a predetermined especially preprogrammed temperature profile along the heating line, which is then realized by the corresponding heating zones/devices and/or cooling zones/devices and the selection thereof.
In order to be able to directly feed externally fed merchandise in the horizontal transport level of the heating device according to the invention to at least one heating line without lifting or lowering the merchandise, at least one of said heating lines can be arranged in the horizontal transport level. Thus, the transportation of the merchandise away from said heating line is facilitated, as the merchandise can be transferred directly to the horizontal transport level by the transportation device, from which it is transported further, without having to additionally lift or lower the merchandise
For the simplified connection to pretreatment or subsequent treatment devices for the merchandise, the feeding and/or transportation device may comprise a transporter provided in front or behind thereof in the direction of transport, via which the merchandise can be fed or removed to or from the heating device from outside. Said transporters transport the merchandise, for instance, to a subsequent treatment device provided behind the heating device in the direction of transport or, in an analogous fashion, from a pretreatment device in the direction towards the heating device.
The transporters and the other components of the heating device according to the invention may be arranged in a housing. In order to prevent protective gas from escaping from the transporters in said housing, said transporters may have lock devices especially with suction implements. Said lock device may be designed like the lock devices disposed between the heating line and the feeding and transportation device.
It is feasible to transport the merchandise along the corresponding heating line in a passive manner, i.e. the article of merchandise is pushed forward by the respectively following article of merchandise, for example, along slide rails or the like. In order to be able, however, to transport the articles of merchandise with a certain distance between each other and to change the transport speed, if required, an oven transporter may be disposed along each heating line. Such an oven transporter may be formed of driven rollers, driven belts, a driven merchandise carrier or the like.
In order to be able to directly and easily feed the merchandise from a transporter to the oven transporter by means of the feeding or transportation device, said feeding or transportation device may comprise a passthrough device connecting the transporter and the oven transporter in the horizontal transport level.
In order to be able to move the merchandise in such a passthrough device forward in the direction of the oven transporter, the passthrough device may comprise a slide or merchandise carrier movable in the direction of transport. Analogously such a slide or merchandise carrier may likewise be disposed in the transportation device.
Another possibility to move the merchandise in the passthrough device can be seen in that the same is provided with rotatable transport rollers. Said rollers may extend transversely to the direction of transport over the total width of the merchandise or may support the same along longitudinal edges.
In order to be able to easily use the slide or merchandise carrier in a circulating manner, they may be movable backwards opposite to the direction of the transport underneath the horizontal transport level in a transporter-associated initial position
With a slide it can be considered advantageous in this connection if the same can be height-adjusted in a vertical direction. During its use it is thereby vertically adjusted towards the top so as to push an article of merchandise from the transporter into the passthrough device. In the following it can be moved downwardly in vertical direction so as to be movable on its way back underneath the horizontal transport level without interfering with additional slides or additional articles of merchandise. The slide may thereby have a lifting mechanism for essentially vertical height adjustment and a driving means essentially movable between the initial position and the discharge position of the slide associated with the heating line
In order to be able to lift or respectively lower the merchandise to the different heating lines directly inside the feeding and/or transportation device; the feeding and/or transportation device may comprise a lifting device for the height-adjustment of the merchandise between heating lines arranged on top of each other,
In the simplest case the lifting device may connect the horizontal transport level, especially in the passthrough device, and an upper transport level disposed vertically above the same with each other. The upper transport level may, for example, correspond with the level of the heating line located on top of the heating line arranged in the horizontal transport level.
If the distance of the horizontal and upper transport level is large enough, the lifting device may use the transport levels arranged between the horizontal and upper transport level as buffer.
In a simple embodiment the lifting device may comprise toothed chains circulating between the horizontal and the upper transport level, which have transport teeth gripping the merchandise from underneath at at least three positions and projecting essentially in the direction of the merchandise. By means of said three positions the merchandise is to be maintained in a horizontal plane and by a synchronous movement of the circulating toothed chains it is to be moved between the different transport levels.
For the safe transport and the safe support of merchandise, two toothed chains may thereby each be arranged opposite each other at rear side faces in the transport direction or at front side faces in the transport direction of the essentially board-shaped merchandise. A total of four transport teeth thereby grip the merchandise from underneath.
In order to be able to achieve a feed to a heating line in the passthrough device, to move merchandise in a vertical direction in the buffer and to feed the merchandise to the at least one additional heating line in the upper transport level, the movement of the lifting device may be clocked. In a first cycle an article of merchandise is, for example, transferred from the passthrough device to the heating line disposed in the horizontal transport level. In the next cycle another article of merchandise is fed to the passthrough device and is arranged in a transport level of the buffer subsequently. During the following cycles another article of merchandise is respectively fed to the passthrough device and is likewise lifted vertically, until, for instance, the buffer is filled and an article of merchandise is likewise arranged in the upper transport level. When the buffer is filled an article of merchandise can each be fed to the respective heating line in the upper and in the horizontal transport level at the same time. Next an article of merchandise is fed from the buffer to the upper transport level and another article of merchandise is fed from the passthrough device again to the buffer, and an article of merchandise is subsequently arranged in the passthrough device. Next the two heating lines may be charged again.
The transport of merchandise by means of the transportation device having a corresponding buffer takes place in an analogous manner.
In order to be able to transfer merchandise to the corresponding heating line in the upper transport level, said heating line may also comprise at least one slide or merchandise carrier for the transfer of the merchandise to the heating line. The slide or merchandise carrier, respectively, may be designed like the corresponding devices of the horizontal transport level and especially the respective transporter, i.e. they may comprise a lifting mechanism and a corresponding driving means. Likewise driven transport rollers may be disposed in the upper transport level.
In the simplest case the lifting devices of the feeding and transportation devices may be designed identically. One lifting device thereby only serves to lift the merchandise and the other serves to lower the merchandise.
In another embodiment of the lifting device the same may comprise an arrangement of lifting or retaining forks disposed next to each other and being vertically and/or perpendicularly adjustable to the direction of transport, each of which comprises a number of transport teeth projecting in the direction of the merchandise. Especially the lifting forks thereby move vertically and perpendicularly to the direction of transport. When the lifting forks move vertically, merchandise correspondingly placed thereon is lifted, whereby associated retaining forks are moved outwardly relative to the direction of transport. Upon moving the retaining forks to the merchandise they grip the same from underneath with the corresponding transport teeth and the lifting forks may be moved away in an outward direction. Said lifting forks are then vertically offset in a downward direction by one transport level, where they grip again a corresponding article of merchandise from underneath. The preceding process is then repeated so that, clocked by the interaction of lifting and retaining forks, the article of merchandise is lifted or respectively lowered with correspondingly reversed movements.
The interaction of lifting and retaining forks may also correspondingly take place such that two retaining forks are associated with a lifting fork, whereby the lifting fork is then located between said two retaining forks. In other words, two lifting forks or retaining forks may each be associated with a retaining fork or a lifting fork, at the ends of which they are disposed in the direction of transport.
In order to be able to transport merchandise away from the area of the lifting or retaining forks in the horizontal and upper transport level, driven transport rollers may be disposed on the lifting and/or retaining forks at least in the area of the horizontal and upper transport level.
A simple embodiment for transporting the merchandise is achieved, for example, in that the transporter and/or the oven transporter comprise two transport belts circulating parallel to the direction of transport and spaced apart from each other, on which lie lateral edges of the merchandise.
In order to be able to extend the heating device according to the invention in an easy manner or to adapt it to changed conditions, the heating lines and/or feeding and/or transportation devices and or transporters may be designed as modules.